Very Easy - 4 wins, 1 loss
Easy - 5 wins, 0 losses
Medium - 4 wins, 1 loss
Balanced - 4 wins, 1 loss
Hard - 3 wins, 2 losses
Insane - 2 wins, 3 losses
Quick summary:
I feel like the bot died pretty quickly in general. Once I figured out how to fight it correctly, it sure didn't seem like it could take as many hits as a normal player in full iron armor. The first round, in Very Easy mode, was actually quite easy but pretty much ended up being a tutorial of sorts.
Some differences in how the bot acts might be welcome, like giving it better gear, more damage, usable potions, etc. A bow mechanic would also be really neat, though that wouldn't be the easiest to implement.
Overall it feels pretty polished. One simple QoL gripe I have, though, is that the world files start you with already-equipped damaged armor and weapons, though that doesn't really matter once you start fighting.
Quick edit: The stopwatch clocked out at ~9 minutes for 30 fights. Not that long, but then again, it wasn't designed to be. At the same time it would be cool to have a balanced mode perhaps with weaker weapons and maybe a larger arena to promote longer battles. Just an idea though.